CN114433860A - A micron-scale succulent porous iron-cobalt alloy and its preparation and application - Google Patents

Abstract

The invention relates to a micron-scale succulent porous iron-cobalt alloy, and preparation and application thereof. The stable vortex domain structure can improve the magnetic storage capacity, and the violent movement of the magnetic moment is beneficial to improving the magnetic loss capacity, so that the material has higher complex permeability. The porous structure increases multiple scattering and optimizes impedance matching. Therefore, compared with the prior art, the fleshy iron-cobalt alloy material has the effective absorption bandwidth of 5.7GHz, the maximum reflection loss of-53.8 dB and excellent electromagnetic wave loss capability in the frequency range of 2.0-18.0 GHz.

Description

A micron-scale succulent porous iron-cobalt alloy and its preparation and application

technical field

The invention belongs to the technical field of functional material preparation, and relates to a micron-scale succulent porous iron-cobalt alloy and its preparation and application.

Background technique

With the rapid development of science and technology and the arrival of the information age, various electronic devices and electronic devices have been closely related to our lives. While people enjoy the convenience brought by it, they cannot ignore the increasingly serious problems of electromagnetic interference and electromagnetic pollution. The use of electronic equipment in industrial and domestic environments has increased many electromagnetic wave emission sources and receivers, resulting in electromagnetic interference and electromagnetic pollution, which not only affects the normal use of electronic equipment, but may also endanger the health of humans and other organisms. In order to reduce electromagnetic interference and electromagnetic pollution, microwave absorbing materials came into being. The loss mechanism of absorbing materials to electromagnetic waves is mainly divided into magnetic loss dominated by magnetic medium and dielectric loss contributed by dielectric and electrical conductors. Among them, magnetic materials have the characteristics of double loss mechanism and are widely used in the field of electromagnetic wave absorption. Magnetic transition metals and alloy materials, such as iron, cobalt, nickel, iron-cobalt alloys, etc., have intrinsic ferromagnetic properties, such as strong saturation magnetization, high Curie temperature, spontaneous magnetization and magnetocrystalline anisotropy, etc., which are beneficial to electromagnetic waves dissipation and improve the microwave absorption performance.

FeCo alloys are important metallic soft magnetic materials, which have attracted much attention due to their unique properties such as high saturation magnetic induction, low coercivity, high permeability, and low magnetic anisotropy constant. These excellent properties make iron-cobalt alloys widely used in many fields such as magnetic recording materials, wave absorbing materials, biotechnology, catalytic catalyst materials and cemented carbide materials. However, the existing iron-cobalt alloy wave-absorbing materials generally have non-porous structures, etc., and their performance in electromagnetic wave absorption and the like still has a large room for improvement.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a micron-scale succulent porous iron-cobalt alloy and its preparation and application.

Through research, it is found that single-component magnetic metal or alloy materials as microwave absorbers still face some obstacles. For example, shortcomings such as narrow absorption bandwidth, weak reflection attenuation, and thick coating hinder their practical application. In addition, the magnetic nanoparticles currently studied have size confinement and a single magnetic domain structure, which usually show relatively weak magnetic losses. In contrast, the assembly of magnetic transition metal alloy materials can achieve tunable anisotropy and change the magnetic domain topology, which is beneficial to improve the complex magnetic permeability. Based on this, a micro-scale succulent porous iron-cobalt alloy material was prepared. By adjusting the hydrothermal reaction time when preparing the precursor, the microstructure of the iron-cobalt alloy will change greatly, and the structure will affect the electromagnetic parameters and impedance matching characteristics of the material, and finally achieve the purpose of accurately regulating the wave-absorbing performance of the magnetic material. Among them, the stable combination of multiple vortex domains helps to improve the magnetic storage capacity and magnetic loss capacity, and helps to enhance the attenuation capacity of the iron-cobalt alloy to electromagnetic waves.

The invention adopts an efficient and simple hydrothermal reaction method to synthesize the precursor cobalt iron oxyhydroxide. After high-temperature reduction in a hydrogen-argon atmosphere, the product particles have good dispersibility and no obvious agglomeration. At the same time, this succulent porous iron-cobalt alloy exhibits excellent comprehensive properties in the field of microwave absorption.

The object of the present invention can be realized through the following technical solutions:

One of the technical solutions of the present invention provides a method for preparing a micron-scale succulent porous iron-cobalt alloy, comprising the following steps:

(1) get ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride, urea and add in deionized water, stir and dissolve, obtain the mixed solution that is transparent pale pink;

(2) the mixed solution is transferred in the reactor, hydrothermally reacted, and the obtained reaction product is washed and dried to obtain an orange precursor powder;

(3) The precursor powder is placed in a hydrogen-argon atmosphere for high-temperature reduction, and then cooled to room temperature to obtain the target product.

Further, in step (1), the molar ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride, and urea is (1-3): (1-4): (4-10): (12-18 ).

Further, in step (1), the addition amount of deionized water satisfies: the Fe ³⁺ concentration in the mixed solution is 0.01-0.03 mol/L.

Further, in step (2), the temperature of the hydrothermal reaction is 80-140° C., and the time is 40-80 min.

Further, in step (2), the washing process is as follows: centrifugal washing with deionized water and ethanol at 8000-10000 rpm for several times.

Further, in step (2), the drying process is as follows: vacuum drying at 60-80°C.

Further, in step (3), the volume fraction of hydrogen in the hydrogen-argon atmosphere used is 4-6%.

Further, in step (3), the high-temperature reduction process is specifically: calcining at 550-650° C. for 1-3 hours.

The second technical solution of the present invention provides a micron-scale succulent porous iron-cobalt alloy, which is prepared by the above-mentioned preparation method. The porous iron-cobalt alloy is succulent and has a size of about 2-3 μm. Nanopore structure.

The third technical solution of the present invention provides the application of a micron-scale fleshy porous iron-cobalt alloy, and the porous iron-cobalt alloy is used as a microwave absorbing material. Specifically, it can be used as an electromagnetic wave absorbing material. In its specific application, the steps are: uniformly mixing the prepared iron-cobalt alloy powder with the sliced paraffin in a mass ratio of 1:1. The mixture was poured into an aluminum mold and pressed into ring samples with an inner diameter of 3.0 mm, an outer diameter of 7.0 mm, and a thickness of 2.0 mm. The complex relative permittivity and permeability were tested in the 2.0-18.0GHz range using a vector network analyzer model N5230C.

Compared with the prior art, the micro-scale succulent porous iron-cobalt alloy of the present invention exhibits the characteristics of high absorption intensity and wide response frequency band, because the center of the vortex domain moves slightly with the magnetic field, the domain wall is basically stable, and the magnetic storage is increased. The magnetic vector near the domain wall vibrates violently, which has strong natural resonance and domain wall resonance effect, which improves the magnetic loss capacity. The strong magnetic coupling between the structural units increases the complex permeability and enhances the magnetic loss. The abundant pore structure increases multiple scattering and multiple reflections, further optimizing impedance matching. This kind of electromagnetic wave absorption performance, strong magnetism, and easy preparation of simple micron-scale succulent porous iron-cobalt alloys have good application prospects.

Description of drawings

Fig. 1 is the scanning electron microscope image and transmission electron microscope image of embodiment 1-4: (a1) the scanning electron microscope image of embodiment 1-succulent iron-cobalt alloy; (a2) the transmission electron microscope image of embodiment 1-succulent iron-cobalt alloy (b1) Scanning Electron Micrograph of Example 2-Spheroidal Iron-Cobalt Alloy; (b2) TEM of Example 2-Spherical Iron-Cobalt Alloy; (c1) Scanning Electron Micrograph of Example 3-Near-Succulent Iron-Cobalt Alloy ; (c2) TEM image of embodiment 3-near succulent iron-cobalt alloy; (d1) scanning electron microscope image of embodiment 4-much succulent iron-cobalt alloy; (d2) embodiment 4-excessive succulent iron-cobalt alloy transmission electron microscope image.

Fig. 2 is the X-ray diffraction spectrum of Example 1 - a succulent iron-cobalt alloy.

FIG. 3 is the relative complex permeability of Example 1-succulent iron-cobalt alloy, including the real part and the imaginary part of the complex permeability.

FIG. 4 is the relative complex permittivity of Example 1-succulent iron-cobalt alloy, including the real part and the imaginary part of the complex permittivity.

Figure 5 shows the reflection loss values of Examples 1-4 at a thickness of 2.0 mm.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

In the following examples, if there is no special description of raw materials or processing techniques, it is indicated that they are all conventional commercially available raw materials or conventional processing techniques in the art.

Example 1:

Preparation of Micron-Scale Succulent Porous Iron-Cobalt Alloys:

First, 1 mmol Fe(NO ₃ ) ₃ .9H ₂ O, 3 mmol Co(NO ₃ ) ₂ .6H ₂ O, 8 mmol NH ₄ F and 15 mmol CO(NH ₂ ) ₂ were weighed respectively, and added to 50 mL of deionized water. Under vigorous magnetic stirring, it was completely dissolved to obtain a homogeneous transparent pale pink solution.

Next, the solution was transferred to a Teflon-lined stainless steel hydrothermal reactor and heated at 120 °C for 1 hour. After cooling to room temperature, centrifugal washing with deionized water and ethanol for several times, vacuum drying at 60 °C, and collection of orange F _x Co _1-x OOH precursor.

Finally, the precursor powder was placed in a ceramic boat and put into a tube furnace, and was reduced at a high temperature of 600 °C for 2 hours in a hydrogen-argon atmosphere (with a hydrogen volume fraction of 5%) at a heating rate of 2 °C/min ^-1 . After cooling down to room temperature naturally, a micron-scale porous iron-cobalt alloy black powder was prepared. Its morphology is similar to succulent, the size is about 2-3 μm, and the surface has a uniformly distributed nanopore structure.

Example 2:

Compared with Example 1, most of the parts are the same, except that in this example: the hydrothermal reaction time is changed to 20 minutes.

Example 3:

Compared with Example 1, most of the parts are the same, except in this example: the hydrothermal time is 40 minutes.

Example 4:

Compared with Example 1, most of the parts are the same, except in this example: the hydrothermal time is 80 minutes.

The microscopic morphology of the micron-scale succulent porous iron-cobalt alloy with controllable morphology in the above embodiment was characterized by scanning electron microscopy (SEM, Hitachi FE-SEM S-4800), and the powder sample was coated on the surface of the conductive adhesive for testing. The microstructure information of a series of alloy materials was characterized by transmission electron microscopy (TEM, JEOL JEM-2100F). The powder samples were ultrasonically dispersed in ethanol, and then dried on a carbon-supported copper grid for testing. X-ray diffraction spectra were measured by Bruker D8 Advance instrument. The complex relative permeability and complex relative permittivity in the range of 2.0-18.0GHz were tested with a vector network analyzer model N5230C, and the reflection loss values at different thicknesses were obtained by calculation and fitting.

Figure 1 shows the scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the succulent porous iron-cobalt alloy synthesized in the above-mentioned examples 1-4. As shown in the figure, the morphology of Example 1 is similar to succulent, and the size is about 2 -3μm, with evenly distributed nanopore structure on the surface. The particle size distribution of the sample is relatively uniform, and the particle dispersibility is good. The shape of Example 2 is similar to a spherical shape, the size is about 2-3 μm, and the surface has a uniformly distributed nanopore structure. Compared with Example 1, due to the shortened hydrothermal time, Example 2 did not evolve into a fleshy shape, and the magnetic domain structure was relatively simple. The shape of Example 3 is similar to that of an unshaped succulent, the size is about 2-3 μm, and the surface has a uniformly distributed nanopore structure. The appearance of Example 4 is similar to that of overripe succulents, the size is about 2-3 μm, the diameter of the nanopores is larger than that of Examples 1-3, and cracks appear on the surface. Therefore, the hydrothermal reaction time is an important condition for the morphology evolution.

FIG. 2 is an X-ray diffraction (XRD) analysis of the above-mentioned Example 1 - a succulent porous iron-cobalt alloy. In the figure, the diffraction peaks located at 2θ=44.75°, 65.13°, and 82.45° correspond to the (110), (200) and (211) crystal planes of simple cubic FeCo (JCPDS No. 49-1567). XRD pattern analysis proves the composition information of the material, and there is no obvious impurity and miscible phase.

Fig. 3 shows the complex permeability real part (μ') and complex permeability imaginary part (μ") of the above-mentioned Example 1-succulent porous iron-cobalt alloy, which are used to reveal the mechanism of its excellent wave absorbing performance (μ _r =μ′–jμ″). The succulent iron-cobalt alloy has multiple vortex domains that exist stably. Compared with the spherical porous iron-cobalt alloy in Example 2, the μ' value is increased to a certain extent, indicating the improvement of the magnetic storage capacity. Under the alternating magnetic field, the magnetic moments near the domain walls vibrate more violently and connect with the surrounding vortex domains, improving the μ″ value and the magnetic loss capability.

Figure 4 shows the real part (ε') and the imaginary part (ε") of the complex dielectric constant (ε') of the above-mentioned Example 1-succulent porous iron-cobalt alloy, which is used to reveal the mechanism of its excellent absorbing performance (ε _r = ε′–jε″). The absorbing properties of materials are mainly derived from the conductance loss and polarization loss ability. Compared with Example 2 - spherical porous iron-cobalt alloy, under the same filler ratio, the connection between the samples in the paraffin matrix decreases due to the increase in the volume of a single succulent particle, and the ε' of the succulent iron-cobalt alloy has a certain value. The decrease in the degree of sluggishness is beneficial to achieve better impedance matching, thereby improving the wave-absorbing properties of the succulent porous iron-cobalt alloy.

FIG. 5 shows the reflection loss values in the frequency range of 2.0-18.0GHz under the thickness of 2.0mm for the above-mentioned Examples 1-4. As shown in the figure, when the thickness of the succulent porous iron-cobalt alloy is 2.0mm, the maximum reflection loss value reaches -53.8dB, and the effective absorption bandwidth is 5.7GHz. Example 2 - Spherical porous iron-cobalt alloy when the sample thickness is 2.0mm, the maximum reflection loss value reaches -16.4dB, and the effective absorption bandwidth is 3.6GHz; Example 3 - nearly succulent iron-cobalt alloy when the sample thickness is 2.0mm , the maximum reflection loss value reaches -23.8dB, and the effective absorption bandwidth is 5.1GHz; Example 4-Excessive fleshy iron-cobalt alloy When the sample thickness is 2.0mm, the maximum reflection loss value reaches -13.5dB, and the effective absorption bandwidth is 2.6GHz . Under the same thickness, the microwave absorption performance of Examples 2-4 is not as good as that of Example 1-succulent porous iron-cobalt alloy, indicating that the hydrothermal reaction time is an important condition for regulating electromagnetic parameters and thus affecting the microwave absorption performance. Micron-scale succulent porous iron-cobalt alloys meet the practical application requirements of strong absorption, broadband response and thin thickness, and are potential high-efficiency absorbing materials.

Example 5:

Compared with Example 1, most of them are the same, except in this example:

The molar ratio of the additions of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride and urea is 3:1:8:15, and the concentration of Fe ³⁺ is 0.06mol/L.

Example 6:

Compared with Example 1, most of them are the same, except in this example:

The molar ratio of the additions of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride and urea is 1:1:8:15, and the concentration of Fe ³⁺ is 0.02mol/L.

Example 7:

Compared with Example 1, most of them are the same, except in this example:

The molar ratio of the additions of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride and urea is 1:1:4:15, and the concentration of Fe ³⁺ is 0.02mol/L.

Example 8:

Compared with Example 1, most of them are the same, except in this example:

The molar ratio of the addition amounts of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride and urea was 2:4:10:15.

Example 9:

Compared with Example 1, most of them are the same, except that in this example, the temperature of the hydrothermal reaction is adjusted to 140°C.

Example 10:

Compared with Example 1, most of them are the same, except that in this example, the temperature of the hydrothermal reaction is adjusted to 80°C.

Example 11:

Compared with Example 1, most of them are the same, except that in this example, the temperature of high-temperature reduction is adjusted to be calcined at 550° C. for 3 hours.

Example 12:

Compared with Example 1, most of them are the same, except that in this example, the temperature of high-temperature reduction is adjusted to be calcined at 650° C. for 1 h.

Example 13:

Compared with Example 1, most of them are the same, except that in this example, the volume fraction of hydrogen in the hydrogen-argon atmosphere used is 4%.

Example 14:

Compared with Example 1, most of them are the same, except that in this example, the volume fraction of hydrogen in the hydrogen-argon atmosphere used is 6%.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (10)

1. A preparation method of a micron-scale succulent porous iron-cobalt alloy is characterized by comprising the following steps:

(1) adding ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium fluoride and urea into deionized water, and stirring for dissolving to obtain a transparent light pink mixed solution;

(2) transferring the mixed solution into a reaction kettle, carrying out hydrothermal reaction, washing and drying the obtained reaction product to obtain orange precursor powder;

(3) and (3) placing the precursor powder in a hydrogen argon atmosphere for high-temperature reduction, and then cooling to room temperature to obtain the target product.

2. The method for preparing the micron-scale succulent porous iron-cobalt alloy according to claim 1, wherein in the step (1), the molar ratio of the iron nitrate nonahydrate to the cobalt nitrate hexahydrate to the ammonium fluoride to the urea is (1-3): (1-4): (4-10): (12-18).

3. The preparation method of the micron-scale succulent porous iron-cobalt alloy as claimed in claim 1, wherein in the step (1), the addition amount of deionized water satisfies the following condition: fe in the mixed solution³⁺The concentration is 0.01-0.03 mol/L.

4. The method for preparing a micron-sized succulent porous Fe-Co alloy according to claim 1, wherein in the step (2), the temperature of the hydrothermal reaction is 80-140 ℃ and the time is 40-80 min.

5. The method for preparing the micron-scale succulent porous iron-cobalt alloy according to claim 1, wherein in the step (2), the washing process is as follows: and adopting deionized water and ethanol to centrifugally wash for several times at the rotating speed of 8000-10000 rpm.

6. The method for preparing the micron-scale succulent porous iron-cobalt alloy according to claim 1, wherein in the step (2), the drying process specifically comprises the following steps: and (3) drying in vacuum at the temperature of 60-80 ℃.

7. The method for preparing the micron-scale succulent porous iron-cobalt alloy according to claim 1, wherein in the step (3), the volume fraction of hydrogen in the hydrogen-argon atmosphere is 4-6%.

8. The preparation method of the micron-scale succulent porous iron-cobalt alloy as claimed in claim 1, wherein in the step (3), the high-temperature reduction process specifically comprises: calcining for 1-3 h at 550-650 ℃.

9. The micron-scale succulent porous iron-cobalt alloy is prepared by the preparation method according to any one of claims 1 to 8, and is characterized in that the porous iron-cobalt alloy is succulent, 2-3 μm in size and nano-pore structures are distributed on the surface of the porous iron-cobalt alloy.

10. Use of a micro-scale succulent porous Fe-Co alloy according to claim 9 as microwave absorbing material.

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